The present invention relates to a multilayer optical recording medium, a method and an apparatus for manufacturing the multilayer optical recording medium. More specifically, the present invention relates to a multilayer optical recording medium having a plurality of intermediate layers each interposed between adjoining optical recording layers, a method and an apparatus for manufacturing such a multilayer optical recording medium.
In order to increase recording capacity of an optical recording medium, a recording method for recording data in multiple layers in addition to increasing recording density in a planar direction has been studied in recent years, and such a method has been gradually put to practical use. Multilayer optical recording medium may have an intermediate layer between adjoining recording layers disposed in a thickness direction of the medium for the purpose of preventing an occurrence of crosstalk between the adjoining recording layers. For example, Japanese Laid-open Patent Publication Nos. 2008-108381 and 2005-259192 disclose methods of manufacturing a multilayer optical recording medium having such an intermediate layer, in which a plurality of recording layer units each consisting of an adhesive layer (intermediate layer) and a recording layer are laminated. According to these methods, a release film is provided on each side of the recording layer unit, and each recording layer unit is adhered and stacked on other recording layer units after the release film thereof is peeled off one at a time.
However, according to the above methods of manufacturing a multilayer optical recording medium, it is inconvenient to handle the recording layer units because they do not have any supporting structure. For this reason, a further improvement on the productivity has been desired. Furthermore, in order to realize high recording density, an improvement on the productivity has been desired while maintaining necessary optical performances of the multilayer optical recording medium.
In view of the above, an object of the present invention is to improve productivity on a multilayer optical recording medium while maintaining satisfactory optical performances of the optical recording medium.